Adjustable landing gear assembly for unmanned aerial vehicles

ABSTRACT

This disclosure describes a configuration of an unmanned aerial vehicle (UAV) landing gear assembly that includes adjustable landing gear extension that may be extended or contracted so that the body of the UAV is contained in a horizontal plane when the UAV is landed, even on sloping surfaces. For example, when a UAV is landing, the slope of the surface may be determined and the landing gear extensions adjusted based on the slope so that the body of the UAV remains approximately horizontal when the UAV lands and is supported by the landing gear extensions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. application Ser. No.14/661,955, filed Mar. 18, 2015, entitled “Adjustable Landing GearAssembly for Unmanned Aerial Vehicles,” which is incorporated herein byreference in its entirety.

BACKGROUND

Unmanned aerial vehicles (“UAV”), such as propeller based aerialvehicles (e.g., quad-copters, octo-copters) are becoming more common.Many UAVs include a navigation or flight control system that is used tocontrol the flight and navigation of the UAV. For proper operation, itis desirable that the navigation or flight control system be calibratedwhen the UAV is horizontal.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical items or features.

FIG. 1 depicts a view of an unmanned aerial vehicle configuration,according to an implementation.

FIG. 2 depicts a view of a landing gear assembly for an unmanned aerialvehicle, according to an implementation.

FIG. 3 illustrates an unmanned aerial vehicle preparing to land on asloping surface, according to an implementation.

FIG. 4 illustrates an unmanned aerial vehicle landing on a slopingsurface, according to an implementation.

FIG. 5 illustrates an unmanned aerial vehicle landed on a slopingsurface, according to an implementation.

FIG. 6 illustrates a landing gear assembly positioned on a surface,according to an implementation.

FIG. 7 illustrates an unmanned aerial vehicle preparing to liftoff,according to an implementation.

FIG. 8 illustrates an unmanned aerial vehicle landed on a surface,according to an implementation.

FIG. 9 illustrates an unmanned aerial vehicle landed on a surface anddisengaging a payload, according to an implementation.

FIG. 10 is a flow diagram of an example unmanned aerial vehicle liftoffprocess, according to an implementation.

FIG. 11 is a flow diagram of an example unmanned aerial vehicle landingprocess, according to an implementation.

FIG. 12 is a flow diagram of an example unmanned aerial vehicle payloaddisengagement process, according to an implementation.

FIG. 13 is a block diagram of an illustrative implementation of anunmanned aerial vehicle control system that may be used with variousimplementations.

While implementations are described herein by way of example, thoseskilled in the art will recognize that the implementations are notlimited to the examples or drawings described. It should be understoodthat the drawings and detailed description thereto are not intended tolimit implementations to the particular form disclosed but, on thecontrary, the intention is to cover all modifications, equivalents andalternatives falling within the spirit and scope as defined by theappended claims. The headings used herein are for organizationalpurposes only and are not meant to be used to limit the scope of thedescription or the claims. As used throughout this application, the word“may” is used in a permissive sense (i.e., meaning having the potentialto), rather than the mandatory sense (i.e., meaning must). Similarly,the words “include,” “including,” and “includes” mean “including, butnot limited to.” Additionally, as used herein, the term “coupled” mayrefer to two or more components connected together, whether thatconnection is permanent (e.g., welded) or temporary (e.g., bolted),direct or indirect (i.e., through an intermediary), mechanical,chemical, optical, or electrical. Furthermore, as used herein,“horizontal” flight refers to flight traveling in a directionsubstantially parallel to the ground (i.e., sea level), and that“vertical” flight refers to flight traveling substantially radiallyoutward from the earth's center. It should be understood by those havingordinary skill that trajectories may include components of both“horizontal” and “vertical” flight vectors.

DETAILED DESCRIPTION

This disclosure describes an adjustable landing gear assembly for anunmanned aerial vehicle (“UAV”) that enables landing of the UAV on anuneven and/or sloping surface, and safe delivery of fragile items. Thelanding gear assembly includes adjustable landing gear extensions thatcontact a surface and support a UAV when landed. The landing gearextensions may each be individually adjusted horizontally with respectto the UAV. Likewise, each of the landing gear extensions may beadjusted by extending or contracting the landing gear extension and/orchanging the angle of the landing gear extension. In one implementation,when a UAV is first powered on or otherwise activated, the angle of thebody of the UAV may be adjusted so that the body of the UAV is containedin a horizontal place that is approximately perpendicular with respectto the gradient of the gravity field of earth. The angle of the body ofthe UAV may be adjusted by extending or contracting one or more of thelanding gear extensions until the body of the UAV is horizontal. Whenthe body of the UAV is determined to be horizontal, the navigationcomponents of the UAV may be calibrated so that navigation and flightcontrols are performed with respect to horizontal and the UAV operatesin an intended manner.

Likewise, when the UAV is landing, it may determine if the surface uponwhich it will land is sloping (not horizontal) or uneven. If the surfaceis sloping, the UAV may extend or contract one or more of the landinggear extensions so that the body of the UAV remains horizontal whenlanding is complete. Adjustment of the landing gear extensions may bedone while the UAV is airborne, as part of the landing process and/orafter the UAV has landed, as discussed further below.

The landing gear assembly may also operate as a landing dampener toabsorb shock resulting from a landing of the UAV to enable safe deliveryof fragile items. For example, when a UAV is landing, the landing gearextensions may be extended and configured to contract as the UAV lands,thereby absorbing forces caused by the landing of the UAV on a surface.In addition, once the UAV has landed, the landing gear extensions may becontracted until a payload carried by the UAV comes into contact withthe surface, or within a defined distance of the surface. When thepayload contacts the surface or is within the defined distance, thepayload may be disengaged from the UAV.

In some implementations, the landing gear assembly may be configured tocouple or decouple from a UAV and/or a variety of differentconfigurations of UAVs. For example, the landing gear assembly mayinclude a support coupling that mates with a receiver coupling that isattached to a body of an UAV. The support coupling may includeelectrical connections that provide power to the landing gear assembly,enable the UAV to control the landing gear assembly, and/or receive datafrom the landing gear assembly. In some implementations, the supportcoupling may be a rotatable member, such as a gimbal, that allows thebody of a coupled UAV to rotate along at least one axis with respect tothe landing gear assembly. For example, prior to liftoff a UAV maydetermine a desired heading of the UAV at liftoff, considering wind orother external forces, and re-orient the body of the UAV to correspondto the desired heading. Specifically, the UAV may be re-oriented whileit is landed by rotating the support coupling so that the body of theUAV rotates while the landing gear assembly remains stationary.

The UAV may be any form of UAV that can be coupled to the landing gearassembly. The UAV may have any number of lifting motors andcorresponding lifting propellers. For example, the UAV may include fourlifting motors and lifting propellers (also known as a quad-copter),eight lifting motors and lifting propellers (also known as anocto-copter), etc. Likewise, to improve the efficiency of horizontalflight, the UAV may also include one or more wings, thrusting motors,etc., that are oriented to aid in horizontal flight of the UAV.

In some implementations, the body of the UAV may be formed of a singlemold or uni-body design. To further improve the efficiency of the UAV,in some implementations, one or more components of the UAV may be formedof one or more lightweight materials, such as carbon fiber, graphite,machined aluminum, titanium, fiberglass, etc. Likewise, one or morecomponents of the landing gear assembly may be formed of lightweightmaterial. Regardless of the material, one or more of the components ofthe UAV and/or the landing gear assembly may be formed having a hollowinner cavity or may be formed around a lightweight core (e.g., foam,wood, plastic), thereby reducing weight, increasing structural rigidityand providing a channel through which one or more wires and/or cablesmay be passed and/or in which other components may be housed.

FIG. 1 illustrates a view of a UAV 100 that is coupled to a landing gearassembly 150, according to an implementation. As illustrated, the UAV100 includes a perimeter frame 104. The perimeter frame 140 includes afront wing 120, a lower rear wing 124, an upper rear wing 122, and twohorizontal side rails 130-1, 130-2. The horizontal side rails 130 arecoupled to opposing ends of the front wing 120 and opposing ends of theupper rear wing 122 and lower rear wing 124. In some implementations,the coupling of the components of the perimeter frame 140 may be with acorner junction. In such an example, the corner junctions are also partof the perimeter frame 104.

The components of the perimeter frame 104, such as the front wing 120,lower rear wing 124, upper rear wing 122, and side rails 130-1, 130-2may be formed of any one or more suitable materials, such as graphite,carbon fiber, aluminum, titanium, etc., or any combination thereof. Inthe illustrated example, the components of the perimeter frame 104 ofthe UAV 100 are each formed of carbon fiber. The components of theperimeter frame 104 may be coupled using a variety of techniques. Forexample, if the components of the perimeter frame 104 are carbon fiber,they may be fitted together and joined using secondary bonding, atechnique known to those of skill in the art. In other implementations,the components of the perimeter frame 104 may be affixed with one ormore attachment mechanisms, such as screws, rivets, latches,quarter-turn fasteners, etc., or otherwise secured together in apermanent or removable manner.

The front wing 120, lower rear wing 124, and upper rear wing 122 arepositioned in a tri-wing configuration and each wing provides lift tothe UAV 100 when the UAV is moving in a direction that includes ahorizontal component. For example, the wings may each have an airfoilshape that causes lift due to the airflow passing over the wings duringhorizontal flight.

Opposing ends of the front wing 120 may be coupled to a corner junctionor the side rails 130. In some implementations, the front wing mayinclude one or more flaps 127 or ailerons, that may be used to adjustthe pitch, yaw, and/or roll of the UAV 100 alone or in combination withthe lifting motors 106, lifting propellers 102, thrusting motors 110,thrusting propellers 112, and/or other flaps on the rear wings,discussed below. In some implementations, the flaps 127 may also be usedas a protective shroud to further hinder access to the liftingpropellers 102 by objects external to the UAV 100. For example, when theUAV 100 is moving in a vertical direction, landed, or hovering, theflaps 127 may be extended to increase the height of the protectivebarrier around a portion of the lifting propellers 102.

In some implementations, the front wing 120 may include two or morepairs of flaps 127. In other implementations, for example, if there isno front thrusting motor 110-1, the front wing 120 may only include asingle flap 127 that extends substantially the length of the front wing120. If the front wing 120 does not include flaps 127, the liftingmotors 106 and lifting propellers 102, thrusting motors 110, thrustingpropellers 112 and/or flaps of the rear wings may be utilized to controlthe pitch, yaw, and/or roll of the UAV 100 during flight.

Opposing ends of the lower rear wing 124 may be coupled to a cornerjunction or to the side rails 130. In some implementations, the lowerrear wing may include one or more flaps 123 or ailerons, that may beused to adjust the pitch, yaw and/or roll of the UAV 100 alone or incombination with the lifting motors 106, lifting propellers 102,thrusting motors 110, thrusting propellers 112, and/or the flaps 127 ofthe front wing. In some implementations, the flaps 123 may also be usedas a protective shroud to further hinder access to the liftingpropellers 102 by objects external to the UAV 100. For example, when theUAV 100 is moving in a vertical direction, landed, or hovering, theflaps 123 may be extended, similar to the extending of the front flaps127 of the front wing 120.

In some implementations, the lower rear wing 124 may include two or moreflaps 123. In other implementations, for example, if there is no rearthrusting motor 110-2 mounted to the lower rear wing, the lower rearwing 124 may only include a single flap 123 that extends substantiallythe length of the lower rear wing 124. In other implementations, if thelower rear wing includes two thrusting motors, the lower rear wing maybe configured to include three flaps 123, one on either end of the lowerrear wing 124, and one between the two thrusting motors mounted to thelower rear wing 124.

Opposing ends of the upper rear wing 122 may be coupled to a cornerjunction or to the side rails 130. In some implementations, like thelower rear wing, the upper rear wing 122 may include one or more flaps(not shown) or ailerons, that may be used to adjust the pitch, yawand/or roll of the UAV 100 alone or in combination with the liftingmotors 106, lifting propellers 102, thrusting motors 110, thrustingpropellers 112, and/or other flaps of other wings. In someimplementations, the flaps may also be used as a protective shroud tofurther hinder access to the lifting propellers 102 by objects externalto the UAV 100. For example, when the UAV 100 is moving in a verticaldirection, landed, or hovering, the flaps may be extended, similar tothe extending of the front flaps 127 of the front wing 120 or the flaps123 of the lower rear wing.

The front wing 120, lower rear wing 124, and upper rear wing 122 may bepositioned and sized proportionally to provide stability to the UAVwhile the UAV 100 is moving in a direction that includes a horizontalcomponent. For example, the lower rear wing 124 and the upper rear wing122 are stacked vertically such that the vertical lift vectors generatedby each of the lower rear wing 124 and upper rear wing 122 are closetogether. In comparison, the front wing 120 is separated from the rearwings longitudinally such that the vertical lift vector generated by thefront wing 120 acts together with the vertical lift vectors of the lowerrear wing 124 and the upper rear wing 122, providing efficiency,stabilization and control.

In one implementation, the UAV 100 may be approximately 64.75 incheslong from the front of the UAV 100 to the rear of the UAV 100 andapproximately 60.00 inches wide. In such a configuration, the front wing120 has dimensions of approximately 60.00 inches by approximately 7.87inches. The lower rear wing 124 has dimensions of approximately 60.00inches by approximately 9.14 inches. The upper rear wing 122 hasdimensions of approximately 60.00 inches by approximately 5.47 inches.The vertical separation between the lower rear wing and the upper rearwing is approximately 21.65 inches. The overall weight of the UAV 100 isapproximately 50.00 pounds.

Coupled to the interior of the perimeter frame 104 is a central frame107. The central frame 107 includes a hub 108 and motor arms that extendfrom the hub 108 and couple to the interior of the perimeter frame 104.In this example, there is a single hub 108 and four motor arms 105-1,105-2, 105-3, and 105-4. Each of the motor arms 105 extend fromapproximately a corner of the hub 108 and couple or terminate into arespective interior corner of the perimeter frame 104. Like theperimeter frame 104, the central frame 107 may be formed of any suitablematerial, such as graphite, carbon fiber, aluminum, titanium, etc., orany combination thereof. In this example, the central frame 107 isformed of carbon fiber and joined at the corners of the perimeter frame104 at corner junctions. Joining of the central frame 107 to theperimeter frame 104 may be done using any one or more of the techniquesdiscussed above for joining the components of the perimeter frame 104.

Lifting motors 106 are coupled at approximately a center of each motorarm 105 so that the lifting motor 106 and corresponding liftingpropeller 102 are within the substantially rectangular shape of theperimeter frame 104. In one implementation, as illustrated in FIG. 1,the lifting motors 106 may be mounted to a top of the motor arms 105 inan upward direction so that the propeller shaft of the lifting motorthat mounts to the lifting propeller 102 is facing upward. In thisexample, there are four lifting motors 106-1, 106-2, 106-3, 106-4, eachmounted to an upper side of a respective motor arm 105-1, 105-2, 105-3,and 105-4.

In some implementations, multiple lifting motors may be coupled to eachmotor arm 105. For example, while FIG. 1 illustrates a quad-copterconfiguration with each lifting motor mounted to a top of each motorarm, a similar configuration may be utilized for an octo-copter. Forexample, the central frame may have a different configuration, such asadditional motor arms. For example, eight motor arms may extend indifferent directions and a lifting motor may be mounted to each motorarm.

The lifting motors may be any form of motor capable of generating enoughrotational speed with the lifting propellers 102 to lift the UAV 100 andany engaged payload, thereby enabling aerial transport of the payload.

Mounted to each lifting motor 106 is a lifting propeller 102. Thelifting propellers 102 may be any form of propeller (e.g., graphite,carbon fiber) and of a size sufficient to lift the UAV 100 and anypayload engaged by the UAV 100 so that the UAV 100 can navigate throughthe air, for example, to deliver a payload to a delivery location. Forexample, the lifting propellers 102 may each be carbon fiber propellershaving a dimension or diameter of twenty-four inches. While theillustration of FIG. 1 shows the lifting propellers 102 all of a samesize, in some implementations, one or more of the lifting propellers 102may be different sizes and/or dimensions. Likewise, while this exampleincludes four lifting propellers 102-1, 102-2, 102-3, 102-4, in otherimplementations, more or fewer propellers may be utilized as liftingpropellers 102. Likewise, in some implementations, the liftingpropellers 102 may be positioned at different locations on the UAV 100.In addition, alternative methods of propulsion may be utilized as“motors” in implementations described herein. For example, fans, jets,turbojets, turbo fans, jet engines, internal combustion engines, and thelike may be used (either with propellers or other devices) to providelift for the UAV.

In addition to the lifting motors 106 and lifting propellers 102, theUAV 100 may also include one or more thrusting motors 110 andcorresponding thrusting propellers 112. The thrusting motors andthrusting propellers may be the same or different from the liftingmotors 106 and lifting propellers 102. For example, in someimplementations, the thrusting propellers may be formed of carbon fiberand be approximately eighteen inches long. In other implementations, thethrusting motors may utilize other forms of propulsion to propel theUAV. For example, fans, jets, turbojets, turbo fans, jet engines,internal combustion engines, and the like may be used (either withpropellers or with other devices) as the thrusting motors.

The thrusting motors and thrusting propellers may be oriented atapproximately ninety degrees with respect to the perimeter frame 104 andcentral frame 107 of the UAV 100 and utilized to increase the efficiencyof flight that includes a horizontal component. For example, when theUAV 100 is traveling in a direction that includes a horizontalcomponent, the thrusting motors may be engaged to provide a horizontalthrust force via the thrusting propellers to propel the UAV 100horizontally. As a result, the speed and power utilized by the liftingmotors 106 may be reduced. Alternatively, in selected implementations,the thrusting motors may be oriented at an angle greater or less thanninety degrees with respect to the perimeter frame 104 and the centralframe 107 to provide a combination of thrust and lift.

In the example illustrated in FIG. 1, the UAV 100 includes two thrustingmotors 110-1, 110-2 and corresponding thrusting propellers 112-1, 112-2.Specifically, in the illustrated example, there is a front thrustingmotor 110-1 coupled to and positioned near an approximate mid-point ofthe front wing 120. The front thrusting motor 110-1 is oriented suchthat the corresponding thrusting propeller 112-1 is positioned insidethe perimeter frame 104. The second thrusting motor is coupled to andpositioned near an approximate mid-point of the lower rear wing 124. Therear thrusting motor 110-2 is oriented such that the correspondingthrusting propeller 112-2 is positioned inside the perimeter frame 104.

While the example illustrated in FIG. 1 illustrates the UAV with twothrusting motors 110 and corresponding thrusting propellers 112, inother implementations, there may be fewer or additional thrusting motorsand corresponding thrusting propellers. For example, in someimplementations, the UAV 100 may only include a single rear thrustingmotor 110 and corresponding thrusting propeller 112. In anotherimplementation, there may be two thrusting motors and correspondingthrusting propellers mounted to the lower rear wing 124. In such aconfiguration, the front thrusting motor 110-1 may be included oromitted from the UAV 100. Likewise, while the example illustrated inFIG. 1 shows the thrusting motors oriented to position the thrustingpropellers inside the perimeter frame 104, in other implementations, oneor more of the thrusting motors 110 may be oriented such that thecorresponding thrusting propeller 112 is oriented outside of theprotective frame 104.

The perimeter frame 104 provides safety for objects foreign to the UAV100 by inhibiting access to the lifting propellers 102 from the side ofthe UAV 100, provides protection to the UAV 100, and increases thestructural integrity of the UAV 100. For example, if the UAV 100 istraveling horizontally and collides with a foreign object (e.g., wall,building), the impact between the UAV 100 and the foreign object will bewith the perimeter frame 104, rather than a propeller. Likewise, becausethe frame is interconnected with the central frame 107, the forces fromthe impact are dissipated across both the perimeter frame 104 and thecentral frame 107.

The perimeter frame 104 also provides a surface upon which one or morecomponents of the UAV 100 may be mounted. Alternatively, or in additionthereto, one or more components of the UAV may be mounted or positionedwithin the cavity of the portions of the perimeter frame 104. Forexample, one or more antennas may be mounted on or in the front wing120. The antennas may be used to transmit and/or receive wirelesscommunications. For example, the antennas may be utilized for Wi-Fi,satellite, near field communication (“NFC”), cellular communication, orany other form of wireless communication. Other components, such ascameras, time of flight sensors, accelerometers, inclinometers,distance-determining elements, gimbals, Global Positioning System (GPS)receiver/transmitter, radars, illumination elements, speakers, and/orany other component of the UAV 100 or the UAV control system (discussedbelow), etc., may likewise be mounted to or in the perimeter frame 104.Likewise, identification or reflective identifiers may be mounted to theperimeter frame 104 to aid in the identification of the UAV 100.

In some implementations, the perimeter frame 104 may also include apermeable material (e.g., mesh, screen) that extends over the top and/orlower surface of the perimeter frame 104 enclosing the central frame,lifting motors, and/or lifting propellers.

A UAV control system 114 is also mounted to the central frame 107. Inthis example, the UAV control system 114 is mounted to the hub 108 andis enclosed in a protective barrier. The protective barrier may providethe control system 114 weather protection so that the UAV 100 mayoperate in rain and/or snow without disrupting the control system 114.In some implementations, the protective barrier may have an aerodynamicshape to reduce drag when the UAV is moving in a direction that includesa horizontal component. The protective barrier may be formed of anymaterials including, but not limited to, graphite-epoxy, Kevlar, and/orfiberglass. In some implementations, multiple materials may be utilized.For example, Kevlar may be utilized in areas where signals need to betransmitted and/or received.

The body of the UAV 100 may be coupled to a landing gear assembly 150that supports the UAV 100 when landed on a surface. As discussed furtherbelow with respect to FIG. 2, the landing gear assembly 150 includes amain support base 153 and one or more landing gear extensions 152-1,152-2, 152-3 that may be adjusted horizontally or extended/contracted toadjust the angle of the body of the UAV when landed. In someimplementations, the landing gear assembly may also include a payloadengagement mechanism (not shown). The payload engagement mechanism maybe configured to engage and disengage a payload 154, such as itemsand/or containers that hold items.

Likewise, the UAV 100 includes one or more power modules (not shown)that may be mounted at various locations on or in the perimeter frame104 and/or the central frame 107. The power modules for the UAV may bein the form of battery power, solar power, gas power, super capacitor,fuel cell, alternative power generation source, or a combinationthereof. For example, the power modules may each be a 6000 mAhlithium-ion polymer battery, or polymer lithium ion (Li-poly, Li-Pol,LiPo, LIP, PLI or Lip) battery. The power module(s) are coupled to andprovide power for the UAV control system 114, the lifting motors 106,the thrusting motors 110, the landing gear assembly 150 and/or thepayload engagement mechanism (not shown).

In some implementations, one or more of the power modules may beconfigured such that it can be autonomously removed and/or replaced withanother power module while the UAV is landed or in flight. For example,when the UAV lands at a location, the UAV may engage with a chargingmember at the location that will recharge the power module. In someimplementations, rather than mounting or including the power modules onthe perimeter frame 104 or the central frame 107, one or more powermodules may be coupled to the landing gear assembly 150. In such animplementation, the landing gear assembly may be loaded with a payloadand charged power modules to which the UAV may be coupled.

FIG. 2 depicts a view of a landing gear assembly 250 for an unmannedaerial vehicle, according to an implementation. As mentioned above withrespect to FIG. 1, the landing gear assembly 250 includes a main supportbase 253 and one or more landing gear extensions 252. In this example,the landing gear assembly includes four landing gear extensions 252-1,252-2, 252-3, 252-4 that may be adjusted horizontally, orextended/contracted to adjust the angle of the body of the UAV whenlanded. Likewise, the angle of each landing gear extension with respectto the main support base may likewise be adjusted. In implementationswith one landing gear extension, the landing gear extension may beadjustable, as described herein, and support a portion of the body ofthe UAV. In such an implementation, the one landing gear extension mayhave a base plate (discussed below) that is of a size sufficient tosupport the UAV when landed. In another configuration, the landing gearextension may support a portion of the body of the UAV and a secondopposing portion of the body of the UAV may contact the surface. Forexample, the landing gear extension may be on one side of the body ofthe UAV and configured to extend or contract until the body of the UAVis approximately horizontal when the opposing side of the UAV iscontacting the surface.

In implementations with two landing gear extensions, the base plates ofeach landing gear extension may be of a size sufficient to support thebody of the UAV when landed and/or the two landing gear extensions maybe positioned to support a portion of the body of the UAV while otherportions of the body of the UAV contact the surface. In implementationswith three landing gear extensions 252, the landing gear extensions maybe arranged in a triangular fashion to enable support of the body of aUAV when the UAV is landed. In configurations with additional landinggear extensions, the landing gear extensions may be arranged to enablesupport of all or a portion of the body of the UAV when landed.Likewise, in some configurations, the body of the UAV may include one ormore fixed or non-adjustable landing gear extensions and one or moreadjustable landing gear extensions.

The landing gear extensions 252 are coupled to the main support base 253and may be adjusted horizontally along the support arms 258. Forexample, each landing gear extension 252 may be adjustably coupled to arespective support arm. Each landing gear extension may be adjustedhorizontally inward toward the center of the landing gear assembly 250or adjusted horizontally outward along the support arm 258 to which itis coupled. The landing gear extensions may be coupled to the supportarms 258 along rails, tracks or other movable components to facilitatehorizontal adjustment. In this example, there are four support arms258-1, 258-1, 258-3, 258-4 and each of the landing gear extensions252-1, 252-2, 252-3, 252-4 are coupled to an underneath side of one ofthe support arms 258.

Each of the landing gear extensions 252 are also adjustable from acontracted position, as illustrated in FIG. 2, to an extended position.When in a fully contracted position, the landing gear extensions are attheir shortest possible length as the adjustable portion of the landinggear extensions is contracted into a fixed portion of the landing gearextension. For example, referring to the expanded view of landing gearextension 252-3, the landing gear extension 252-3 includes an outerfixed portion 256-1 and an inner adjustable portion 256-2 that may beextended or contracted with respect to the fixed portion 256-1. In thisexample, the inner adjustable portion 256-2 is a threaded extension thatmates with threads on an inner side of the fixed portion 256-1. When theadjustable portion is rotated in a first direction, the threads causethe adjustable portion 256-2 to extend from the fixed portion 256-1 sothat the landing gear extension adjusts from a contracted position to anextended position. When the adjustable portion is rotated in a seconddirection, the threads cause the adjustable portion 256-2 to contractinto the fixed portion 256-1, so that the landing gear extension isadjusted from an extended position to a contracted position. Theadjustable portion may be coupled to and rotated by a motor, such as aservo motor.

The landing gear extensions may use any one or more mechanisms forcontracting and extending the landing gear extension. For example, thelanding gear extension may include a hydraulic arm, a pneumatic arm, amagnetically adjustable arm, threaded extensions as illustrated in FIG.2, a linear gear extension, a telescoping arm, etc. In eachconfiguration, the landing gear extension includes an appropriate driveor motor to facilitate adjustment of the landing gear extension. In someimplementations, the landing gear extensions may be configured such thatthe adjustable portion of the landing gear extension may be separated orejected from the landing gear extension. For example, if the UAV islanded and preparing to liftoff, it may be determined that one or moreof the landing gear extensions has malfunctioned and/or the adjustableportion of the landing gear extension is stuck in the surface (e.g., mudor ice). In such an implementation, the adjustable portion of thelanding gear extension may be ejected or otherwise separated from thelanding gear assembly to enable liftoff by the UAV.

Each landing gear extension may also include a base plate 257 that ispositioned at the end or foot of the landing gear extension 252. Thebase plate 257 may be of any size and/or shape. For example, asillustrated in FIG. 2, the base plate 257 may have a substantiallycylindrical shape to facilitate a firm contact with a sloping surface.In other implementations, the base plate 257 may have a large surfacearea to provide increased contact between the base plate 257 and thesurface. In one implementation, there may only be two landing gearextensions and each landing gear extension may have a base plate with alarge flat surface area that provides sufficient contact between thebase plates and the surface to support the UAV. Likewise, in someimplementations, the base plate may be rotatable about one or more axiswith respect to the landing gear extension.

The base please 257 may also include one or more sensors, such as acontact sensor. The contact sensor may be positioned on a lower portionof the base plate 257 and configured to detect when the landing gearextension contacts a surface. The contact sensor may be any type ofpressure sensor, load cell, etc., that is capable of detecting a contactwith another object. The contact sensor may also be configured to detecta surface type and/or a surface material (e.g., earth, stone, compositeroof, ice, metal). In other implementations, the surface type and/orsurface material may be determined based on one or more images obtainedof the surface that are processed to determine the surface type and/orsurface material.

The base plate 257, in some implementations, may also include a surfaceengagement member, such as the surface engagement member 259 illustratedin FIG. 2. The surface engagement member may be configured to increase acontact between the landing gear extension 252 and the surface and/or tosecure the landing gear extension 252 to the surface. Depending on thesurface type and/or surface material, different surface engagementmembers 259 may be utilized. For example, as illustrated in FIG. 2, thesurface engagement member 259 may be in the form of a barbed spike thatmay be extended or contracted from the base pate 257 to secure thelanding gear extension 252 to a surface. The surface engagement member259 illustrated in FIG. 2 may be utilized when the UAV is landed on anearth surface to secure the landing gear extension 252 to the earth.Likewise, if the UAV is landed on ice, snow, or other similar material,the surface engagement member 259 illustrated in FIG. 2 may likewise beextended from the base plate 257 to increase or secure the landing gearextension 252 to the surface. In other implementations, other forms ofsurface engagement members may be utilized. For example, rather than abarbed spike, the surface engagement member may be in the form of abarbless spike and/or a threaded screw that may be rotated and screwedinto the surface. As another example, one or more of the landing gearextensions 252 may include a surface engagement member in the form of amagnet or electromagnet for securing the landing gear extension 252 to ametallic surface. In still another example, one or more of the landinggear extensions may include a surface engagement member in the form of avacuum suction cup that may be engaged to secure the landing gearextension 252 to a flat surface. In some implementations, one or more ofthe landing gear extensions 252 of a landing gear assembly 250 mayinclude the same or different types of surface engagement members 259.

One or more of the landing gear extensions may also include a distancedetermining element 261 that is configured to determine a distancebetween the distance determining element and an object, such as asurface. The distance determining elements 261 may be any form of devicethat can be used to measure a distance between an object and thedistance determining element. For example, the distance determiningelements 261 may be any one of an ultrasonic ranging module, a laserrangefinder, a radar distance measurement module, a stadiametric basedrangefinder, a parallax based rangefinder, a coincidence basedrangefinder, a Lidar based rangefinder, Sonar based range finder, or atime-of-flight based rangefinder. In some implementations, differentdistance determining elements may be utilized on the UAV and/or thelanding gear assembly.

As discussed further below, the determined distances between each of thelanding gear extensions and/or the detected contact of a landing gearextension with an object may be provided to a landing gear controller.The landing gear controller may determine a slope of a surface on whichthe UAV will land and send instructions to adjust (expand/contract) oneor more of the landing gear extensions so that the body of the UAVremains horizontal when the UAV is landed.

Coupled to an upper side of the main support base may be a supportcoupling 260 that enables the landing gear assembly to be selectivelycoupled or decoupled from a body of a UAV, such as the UAV 100 discussedabove with respect to FIG. 1. For example, the support coupling may haveone or more grooves, ridges or attachment locations to which a receivercoupling that is mounted to an underneath side of the body of a UAV cancouple. For example, a receiver coupling may be mounted to an underneathside of the hub 108 of the central frame 107 of the UAV 100 (FIG. 1) andthe support coupling may be configured to couple with the receivercoupling.

The support coupling may include one or input/output contacts 262 thatmay be utilized to exchange data between the landing gear assembly andthe UAV control system 114, to provide power from a power module of theUAV to the landing gear assembly 250, to provide power from a powermodule of the landing gear assembly to the UAV, and/or to provide othermaterials such as liquid and/or gas that may be used to operate one ormore of the landing gear extensions 252. For example, if the landinggear extension 252 includes a hydraulic arm, a liquid may be providedfrom a liquid storage reservoir mounted to a body of the UAV through oneof the input/output contacts 262 and used to adjust the landing gearextension 252. In other implementations, the liquid, gas, or othermaterial(s) used to adjust the landing gear extensions may be includedas part of the landing gear assembly, or contained in the respectivelanding gear extension.

In some implementations, the support coupling 260 may be rotatable aboutone or more axis. For example, the support coupling 260 may include agimbal or other rotatable component. When the UAV is landed, the supportcoupling may be used to rotate the body of the UAV about an axis whilethe landing gear assembly remains stationary. Allowing rotation of thebody of the UAV enables the UAV to orient in the approximate directionof a desired heading of the UAV before the UAV lifts off from thesurface. This may be particularly desirable when the UAV includes one ormore wings. By orienting the UAV in the desired heading, for exampleinto the wind, the UAV remains more stable during liftoff.

When the UAV is airborne, the support coupling may be used to rotate thelanding gear assembly about an axis without rotating the body of theUAV. Allowing rotation of the landing gear assembly allows the UAV toposition the landing gear assembly and position the landing gearextensions at orientations that will engage the surface at desiredpoints and provide the greatest stability for the UAV while landed.Rather than having to reorient the UAV, which may result in undesiredcrosswinds, etc., the landing gear assembly may be rotated using thesupport coupling.

While the examples herein discuss a landing gear assembly that may becoupled and decoupled from a body of a UAV, in other configurations, thelanding gear assembly may be incorporated into a part of the UAV.

As mentioned above, the landing gear assembly 250 may also include apayload engagement mechanism that is configured to engage and disengagea payload 254, such as items and/or containers that hold items. In thisexample, the payload engagement mechanism is positioned beneath andcoupled to an underneath side of the support arms 258 and the supportcoupling 260. The payload engagement mechanism may be of any sizesufficient to securely engage and disengage a payload 254. In otherimplementations, the payload engagement mechanism may operate as thecontainer in which it contains item(s). The payload engagement mechanismcommunicates with (via wired or wireless communication) and iscontrolled by the UAV control system 114. For example, the UAV controlsystem 114 may send instructions to the payload engagement mechanism viathe input/output contacts 262. Example payload engagement mechanisms aredescribed in co-pending patent application Ser. No. 14/502,707, filedSep. 30, 2014, titled “UNMANNED AERIAL VEHICLE DELIVERY SYSTEM,” thesubject matter of which is incorporated by reference herein in itsentirety.

With the implementations described herein, the landing gear assembly,when coupled to a UAV, allows the UAV to land on sloping and/or unevensurfaces while keeping the body of the UAV horizontal. When the UAV ishorizontal, one or more components of the UAV control system 114 may becalibrated so that the UAV operates in an efficient and safe manner.

Establishing horizontal may be done at a variety of times. For example,when the UAV first powers on, it may engage the landing gear assemblyand adjust one or more of the landing gear extensions until it isdetermined that the body of the UAV is horizontal. It may be determinedthat the body of the UAV is horizontal using one or more sensors. Thesensors may be any type of sensor that can be configured to determine anangle or whether the body of the UAV is horizontal. For example, thesensor may be an accelerometer, an inclinometer, a manometer, amechanical level, etc. In one implementation, a measurement unit, one ormore components (e.g., navigation system) of the UAV control system,and/or one or more other points of reference may be utilized todetermine when the body of the UAV is approximately horizontal. Forexample, rather than the entire body of the UAV being horizontal, thelanding gear assembly may be adjusted until the measurement unit,component(s) of the UAV control system, and/or other point of referenceis approximately horizontal. When the measurement unit, component(s),and/or other point of reference is approximately horizontal, the body ofthe UAV is considered to be horizontal. Once it is determined that thebody of the UAV is horizontal, the flight system may be calibrated.

In another implementation, as illustrated in FIGS. 3-5, as a UAV islanding, it may determine a slope of the surface upon which it will landand extend or contract one or more of the landing gear extensions sothat the body of the UAV will be horizontal when the UAV contacts thesurface.

Referring first to FIG. 3, which illustrates an unmanned aerial vehicle300 preparing to land on a sloping surface, according to animplementation, one or more distance determining elements 360 of the UAVmay be used to determine a slope of the surface. In this example, theUAV and/or the landing gear assembly includes a distance determiningelement 360 in the form of an ultrasonic sensor that is configured tomeasure the distance at several points between the distance determiningelement and the surface. Based on the measured distances, the landinggear controller determines an approximate slope or topology of thesurface and determines which landing gear extensions need to be extendedor contracted so that the body of the UAV remains approximatelyhorizontal after the UAV has landed on the sloping surface.

For example, referring to FIG. 6, if the surface 602 has approximately aten degree slope, the landing gear controller can determine that if thelanding gear extension 652-3 is contracted to a length of approximately12.00 inches and has an angle of 100 degrees with respect to the mainsupport base 653 (or ten degrees past vertical), the landing gearcontroller can compute and determine the length and angles for the otherlanding gear extensions that are needed so that the main support base653 is approximately horizontal. In this example, if the distancebetween the first landing gear extension 652-2 and the second landinggear extension is approximately 50.00 inches, it can be computed thatthe second landing gear extension 652-3 should have an angle ofapproximately 95 degrees with respect to the main support base 653 (fivedegrees past vertical) and a length of approximately 21.41 inches. Asimilar computation may be used to determine the angle and length ofother landing gear extensions.

Based on the computed angles and lengths of the landing gear extensions,the landing gear controller sends instructions to each landing gearextension to extend or contract to the determined length and positionthe landing gear extension at the determined angle. Adjustments to thelanding gear extensions may be done prior to the UAV contacting thesurface so that the landing gear extensions are at approximately theappropriate lengths, after contact between a landing gear extension andthe surface is detected, or after the UAV has landed. In oneimplementation, the landing gear extensions are adjusted to theappropriate lengths and angles prior to landing and, once the UAV haslanded, any final adjustments to the lengths of the landing gearextensions may be made so that the main support base and the body of theUAV 300 are approximately horizontal. Once the body of the UAV isdetermined to be horizontal, the UAV may power down, calibrate the UAVcontrol system, and/or perform other functions.

FIG. 4 illustrates another example for adjusting a UAV 400 utilizing thelanding gear extensions 452, according to an implementation. In thisexample, the ends of the landing gear extensions 452 that contact thesurface 402 each include contact sensors configured to detect when thelanding gear extension has contacted the surface. As the UAV 400descends toward the surface, the landing gear extensions are eachmaintained in a contracted or partially contracted position. The UAVcontinues to descend until a first landing gear extension 452-2 detectsa contact between the landing gear extension 452-2 and the surface 402.When contact is detected, the UAV control systems continue to operatethe motors and propellers of the UAV to keep the body of the UAVapproximately horizontal. Likewise, the landing gear controller adjuststhe landing gear extensions until contact with the other landing gearextensions and the surface are detected. In this example, the landinggear controller adjusts landing gear extensions 452-1, 452-3, 452-4until each contact the surface 402. Once contact between the surface andeach landing gear extension is detected, the UAV control system maypower down the motors. The landing gear controller may also make anyfinal adjustments to the landing gear extensions until the body of theUAV is determined to be approximately horizontal.

While FIG. 4 describes an example of descending toward a surface withthe landing gear extensions contracted and then extending the landinggear extensions once a first contact is detected, in anotherimplementation, the UAV may descend toward a surface with the landinggear extensions either fully or partially extended. In such an example,the contact sensors may be used to monitor for a first contact betweenan extended landing gear extension and the surface. When a first contactis detected, the UAV control system continues to operate the motors andpropellers of the UAV to keep the body of the UAV approximatelyhorizontal and to continue descent of the UAV toward the surface.Likewise, the landing gear controller adjusts the landing gear extensionthat has contacted the surface by contracting the landing gear extensionuntil a second contact between the surface and a second extended landinggear extension is detected. This process of descending and contractingthe landing gear extensions continues until all of the landing gearextensions have contacted the surface and the body of the UAV isapproximately horizontal.

FIG. 5 illustrates a UAV 500 landed on a sloping surface 502, accordingto an implementation. In this example, the UAV 500 has adjusted thelanding gear extensions 552-1, 552-2, 552-3, 552-4 so that the UAV isapproximately horizontal when landed and supported by the landing gearextensions 552. The adjustments may be performed using any of thetechniques discussed herein. In this example, the landing gearextensions 552-1, 552-2 are contracted and have a first length and afirst angle. The landing gear extensions 552-3, 552-4 have been adjustedto extended positions and have second lengths. As illustrated, thesecond length is greater than the first length. While this example showsthe landing gear extensions 552-1, 552-2 in contracted positions eachhaving a first length and the landing gear extensions 552-3, 552-4 eachbeing in extended positions and each have a second length, it will beappreciated that each landing gear extension 552-1, 552-2, 552-3, 552-4may each have different lengths and/or angles with respect to the mainsupport surface of the landing gear assembly.

FIG. 7 illustrates a UAV preparing to liftoff from a surface 702,according to an implementation. In this example, the landing gearassembly 750 is coupled to the UAV 700 with a rotatable support coupling(not shown). Prior to liftoff, the UAV control system determines adesired heading of the UAV at liftoff. The desired heading may be basedon, for example, the direction and speed of the wind, the planned flightpath of the UAV, and/or other factors. In this example, because the UAV700 includes wings 720, 722, it may be beneficial to orient the UAV 700into the wind prior to liftoff so that the wind crossing over the wings720, 722 will provide lift to the UAV and not cause undesired forces onthe UAV.

Based on the desired heading of the UAV, the UAV 700 is rotated about anaxis using the support coupling so that the UAV is oriented in thedirection of the desired heading, as illustrated. As illustrated, theUAV 700 rotates about the axis while the UAV is landed, and the landinggear assembly 750 and corresponding landing gear extensions 752-1,752-2, 752-3, 752-4 remain approximately stationary.

FIG. 8 illustrates a UAV 800 landed on a surface 802, according to animplementation. In this example, the landing gear extensions 852-1,852-2, 852-3, 852-4 are positioned in an extended, or partially extendedposition prior to landing and configured to compress as the UAV 800lands to absorb shock forces resultant from the landing. For example, ifthe landing gear extensions are hydraulic, the landing gear extensionsmay be configured to release or expel an amount of fluid when the UAVlands so that the landing gear extensions 852 effectively act as shockabsorbers dampening the impact from landing. Using the landing gearextensions to absorb forces caused at landing, the UAV 800 and anyengaged payload 854 receives less impact from the landing. By reducingforces affecting the payload 854, the UAV may be utilized to deliverfragile items, such as glass, without damaging the items during landing.

In addition to absorbing shock forces from the landing, the landing gearextensions are extended to a length so that the payload 854, which isengaged by the payload engagement mechanism 862 will not contact thesurface 802 when the UAV 800 lands.

Turning to FIG. 9, illustrated is a UAV 900 landed on a surface 902 anddisengaging a payload 954, according to an implementation. After the UAVhas landed, the landing gear controller may cause the landing gearextensions 952-1, 952-2, 952-3, 952-4 to contract until the payload 954contacts the surface or is a defined distance (e.g., 0.5 inches) abovethe surface 902. Contact between the payload 954 and the surface 902, ordetecting the defined distance there between, may be done in a varietyof manners. For example, the payload engagement mechanism 962 mayinclude distance determining elements that can determine a distance fromthe surface. In other implementations, the payload engagement mechanismmay detect a change in force when the payload 954 contacts the surface.In still another example, the contact sensors included in the landinggear extensions 952 may detect a change in pressure resulting from thepayload contacting the surface.

Upon determining that the payload has contacted the surface and/or ispositioned a defined distance above the surface, the payload may bedisengaged by the payload engagement mechanism 962 such that the payloadis disengaged from the UAV 900, thereby delivering the payload. Afterdisengaging the payload, the landing gear controller may cause thelanding gear extensions to extend to create a separation between thepayload engagement mechanism 962 and the payload 954. Likewise, the UAVcontrol system may cause the UAV 900 to liftoff, or perform otherfunctions.

FIG. 10 is a flow diagram of an example unmanned aerial vehicle liftoffprocess 1000, according to an implementation. The example process 1000,and each other process described herein, may be implemented by thearchitectures described herein or by other architectures. The processesare illustrated as a collection of blocks in logical flow graphs. Someof the blocks represent operations that can be implemented in hardware,software, or a combination thereof. In the context of software, theblocks represent computer-executable instructions stored on one or morecomputer readable media that, when executed by one or more processors,perform the recited operations. Generally, computer-executableinstructions include routines, programs, objects, components, datastructures, and the like that perform particular functions or implementparticular abstract data types.

The computer readable media may include non-transitory computer readablestorage media, which may include hard drives, floppy diskettes, opticaldisks, CD-ROMs, DVDs, read-only memories (ROMs), random access memories(RAMs), EPROMs, EEPROMs, flash memory, magnetic or optical cards,solid-state memory devices, or other types of storage media suitable forstoring electronic instructions. In addition, in some implementations,the computer readable media may include a transitory computer readablesignal (in compressed or uncompressed form). Examples of computerreadable signals, whether modulated using a carrier or not, include, butare not limited to, signals that a computer system hosting or running acomputer program can be configured to access, including signalsdownloaded through the Internet or other networks. Finally, the order inwhich the operations are described is not intended to be construed as alimitation, and any number of the described operations can be combinedin any order and/or in parallel to implement the process.

The example process 1000 begins when the UAV is powered up, or receivesa liftoff instruction, as in 1002. For example, after a UAV hascompleted a delivery of a payload, it may receive instructions, whichinclude a liftoff instruction, to navigate to another destination. Asanother example, if the UAV has been charging, it may be scheduled topower up and depart at a defined period of time or after charging of thepower modules of the UAV is complete.

As part of the example process 1000, the UAV landing gear controller maydetermine if the UAV is horizontal and adjust one or more of the landinggear extensions until it is determined that the body of the UAV isapproximately horizontal, as in 1004. For example, if it is determinedthat the body of the UAV is at an angle, one or more of the landing gearextensions may be expanded while others are contracted until the body ofthe UAV is horizontal.

Once the body of the UAV is horizontal, the one or more components ofthe UAV control system, such as an inertial measurement unit (“IMU”), iscalibrated so that it corresponds with the determined horizontalposition of the body of the UAV, as in 1006. Calibration of componentsis known to those of skill in the art and will not be discussed indetail herein.

In addition to calibrating components of the UAV control system, thedesired heading of the UAV at liftoff is determined, as in 1008. Thedesired heading may be determined based on the direction of the windand/or the wind speed, the intended flight path of the UAV, etc. Basedon the determined desired heading of the UAV at liftoff, the body of theUAV is rotated about an axis so that it is oriented in the direction ofthe desired heading, as in 1010. For UAVs in which the direction ororientation is not important (e.g., UAV with no wings), blocks 1008-1010may be omitted. However, for UAVs that have an orientation (e.g., UAVwith wings), rotating the UAV to correspond with the desired heading maybe beneficial for ensuring a stable liftoff and/or to improve efficiencyof the UAV. As discussed above, the body of the UAV may be coupled tothe landing gear assembly at a support coupling that enables the body ofthe UAV to rotate about an axis while the landing gear assembly remainsstationary. After orienting the UAV to correspond with the desiredheading, the UAV may liftoff, as in 1012.

FIG. 11 is a flow diagram of an example UAV landing process 1100,according to an implementation. The example process 1100 begins bynavigating the UAV toward a surface, as in 1102. As the UAV isapproaching the surface, the slope of the surface is determined, as in1104. As discussed above, the UAV and/or the landing gear assembly mayinclude a distance determining element that is configured to measuredistances between the UAV and the surface. The measured distances may beutilized to determine the slope of the surface.

Based on the determined slope of the surface upon which the UAV willland, one or more of the landing gear extensions are adjusted by eithercontracting or extending the landing gear extensions so that the landinggear extensions correspond with the surface slope, as in 1106. Forexample, as discussed above with respect to FIG. 6, a length and angleof one of the landing gear extensions may be set and the length andangle of the other landing gear extensions may be computed based on thedetermined slope of the surface so that the body of the UAV will remainapproximately horizontal when the UAV lands on the surface.

As the UAV descends, contact between one or more of the landing gearextensions and the surface is determined, as in 1108. For example, asdiscussed above, the landing gear extensions may include contact sensorsthat detect contact between the landing gear extension and the surface.In another implementation, contact may be detected by the UAV controlsystem due to a change in force or detected impact resulting from thecontact between the landing gear extension and the surface.

When one or more of the landing gear extensions contact the surface, theUAV control system continues operating the motors and maintains the bodyat an approximately horizontal position, as in 1110. While the body ofthe UAV remains approximately horizontal, the landing gear extensionsare adjusted until all the landing gear extensions are in contact withthe surface and the body of the UAV is horizontal, as in 1112.

After landing, it is confirmed that the body of the UAV is horizontal,as in 114, and any additional adjustments to one or more of the landinggear extensions are made until the body of the UAV is approximatelyhorizontal. Once it is confirmed that the body of the UAV isapproximately horizontal, the example process 1100 completes, as in1116.

The example process 1100 provides one implementation for adjusting thelanding gear extensions during landing of the UAV so that the body ofthe UAV remains horizontal when landed and supported by the landing gearassembly. It will be appreciated that other techniques may likewise beutilized. For example, rather than detecting a slope of the surfaceand/or adjusting the landing gear extensions while landing, the UAV mayland and then one or more of the landing gear extensions may be adjusteduntil the body of the UAV is determined to be horizontal. In anotherexample, the example process may not determine the slope of the surfaceand may just monitor for a contact between one or more of the landinggear extensions, as discussed above with respect to block 1108. Oncecontact is detected, as in 1108, the remainder of the example process1100 may be performed. In yet another example, the surface slope may bedetected (1104) and the landing gear extensions adjusted to correspondwith the surface slope (1106). However, rather than detecting contact(1108) and maintaining the body of the UAV at approximately horizontal(1110) while further landing gear extension adjustments are made (1112),the UAV may land, then confirm that the body of UAV is approximatelyhorizontal and make any final adjustments to the landing gear extensionsafter landing.

FIG. 12 is a flow diagram of an example UAV payload disengagementprocess 1200, according to an implementation. The example process beginsby landing a UAV that includes a payload, as in 1202. As discussed abovewith respect to FIG. 8, in some implementations, the landing gearextensions may be adjusted so that the payload will not contact thesurface when the UAV lands. Likewise, the landing gear extensions may beconfigured to absorb some or all of the forces resultant from thelanding.

Once the UAV has landed, the landing gear extensions may be adjusteduntil the payload contacts the surface or is within a defined distance(e.g., 0.5 inches) from the surface, as in 1204. For example, thelanding gear extensions may each contract a defined amount, effectivelylowering the payload (and the UAV) closer to the surface.

Once the payload has contacted the surface or is within the defineddistance of the surface, the payload is disengaged, as in 1206. Forexample, if the payload engagement mechanism includes a servo motor thatcontrols arms that selectively engage or disengage a payload, theservomotor may cause the arms to disengage the payload. Upondisengagement of the payload from the UAV, the example process 1200completes, as in 1208.

FIG. 13 is a block diagram illustrating an example UAV control system1314. In various examples, the block diagram may be illustrative of oneor more aspects of the UAV control system 114 that may be used toimplement the various systems and methods discussed herein and/or tocontrol operation of the UAVs described herein. In the illustratedimplementation, the UAV control system 1314 includes one or moreprocessors 1302, coupled to a memory, e.g., a non-transitory computerreadable storage medium 1320, via an input/output (I/O) interface 1310.The UAV control system 1314 may also include electronic speed controls1304 (ESCs), power supply modules 1306, a navigation system 1307, apayload engagement controller 1312, and/or a landing gear controller1328. In some implementations, the navigation system 1307 may include anIMU. The UAV control system 1314 may also include a network interface1316, and one or more input/output devices 1318.

In various implementations, the UAV control system 1314 may be auniprocessor system including one processor 1302, or a multiprocessorsystem including several processors 1302 (e.g., two, four, eight, oranother suitable number). The processor(s) 1302 may be any suitableprocessor capable of executing instructions. For example, in variousimplementations, the processor(s) 1302 may be general-purpose orembedded processors implementing any of a variety of instruction setarchitectures (ISAs), such as the x86, PowerPC, SPARC, or MIPS ISAs, orany other suitable ISA. In multiprocessor systems, each processor(s)1302 may commonly, but not necessarily, implement the same ISA.

The landing gear controller 1328 may communicate with the landing gearassembly sending instructions to adjust the landing gear extensions. Insome implementations, the landing gear controller may also include adevice that may be used to determine if the body of the UAV isapproximately horizontal. For example, the landing gear controller mayinclude a digital level, an accelerometer, a gyroscope, or othercomponent that can measure or determine an angle or tilt of an object.In other implementations, the landing gear controller may receiveinformation from the navigation system 1307 indicating whether the bodyof the UAV is horizontal.

In other implementations, the landing gear controller may not beincluded in the UAV control system and may be part of the landing gearassembly. In such an implementation, the landing gear controller maycommunicate with the UAV control system via wired and/or wirelesscommunication.

The non-transitory computer readable storage medium 1320 may beconfigured to store executable instructions, data, flight paths, flightcontrol parameters, and/or data items accessible by the processor(s)1302. In various implementations, the non-transitory computer readablestorage medium 1320 may be implemented using any suitable memorytechnology, such as static random access memory (SRAM), synchronousdynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type ofmemory. In the illustrated implementation, program instructions and dataimplementing desired functions, such as those described herein, areshown stored within the non-transitory computer readable storage medium1320 as program instructions 1322, data storage 1324 and flight controls1326, respectively. In other implementations, program instructions,data, and/or flight controls may be received, sent, or stored upondifferent types of computer-accessible media, such as non-transitorymedia, or on similar media separate from the non-transitory computerreadable storage medium 1320 or the UAV control system 1314. Generallyspeaking, a non-transitory, computer readable storage medium may includestorage media or memory media such as magnetic or optical media, e.g.,disk or CD/DVD-ROM, coupled to the UAV control system 1314 via the I/Ointerface 1310. Program instructions and data stored via anon-transitory computer readable medium may be transmitted bytransmission media or signals, such as electrical, electromagnetic, ordigital signals, which may be conveyed via a communication medium suchas a network and/or a wireless link, such as may be implemented via thenetwork interface 1316.

In one implementation, the I/O interface 1310 may be configured tocoordinate I/O traffic between the processor(s) 1302, the non-transitorycomputer readable storage medium 1320, and any peripheral devices, thenetwork interface 1316 or other peripheral interfaces, such asinput/output devices 1318 and/or the landing gear controller, if it isseparate from the UAV control system. In some implementations, the I/Ointerface 1310 may perform any necessary protocol, timing or other datatransformations to convert data signals from one component (e.g.,non-transitory computer readable storage medium 1320) into a formatsuitable for use by another component (e.g., processor(s) 1302). In someimplementations, the I/O interface 1310 may include support for devicesattached through various types of peripheral buses, such as a variant ofthe Peripheral Component Interconnect (PCI) bus standard or theUniversal Serial Bus (USB) standard, for example. In someimplementations, the function of the I/O interface 1310 may be splitinto two or more separate components, such as a north bridge and a southbridge, for example. Also, in some implementations, some or all of thefunctionality of the I/O interface 1310, such as an interface to thenon-transitory computer readable storage medium 1320, may beincorporated directly into the processor(s) 1302.

The ESCs 1304 communicate with the navigation system 1307 and adjust therotational speed of each lifting motor and/or the thrusting motor tostabilize the UAV and guide the UAV along a determined flight path. Thenavigation system 1307 may include a GPS, indoor positioning system(IPS), IMU or other similar systems and/or sensors that can be used tonavigate the UAV 100 to and/or from a location. The payload engagementcontroller 1312 communicates with actuator(s) or motor(s) (e.g., aservomotor) used to engage and/or disengage items.

The network interface 1316 may be configured to allow data to beexchanged between the UAV control system 1314, other devices attached toa network, such as other computer systems (e.g., remote computingresources), and/or with UAV control systems of other UAVs. For example,the network interface 1316 may enable wireless communication between theUAV that includes the control system 1314 and a UAV control system thatis implemented on one or more remote computing resources. For wirelesscommunication, an antenna of an UAV or other communication componentsmay be utilized. As another example, the network interface 1316 mayenable wireless communication between numerous UAVs. In variousimplementations, the network interface 1316 may support communicationvia wireless general data networks, such as a Wi-Fi network. Forexample, the network interface 1316 may support communication viatelecommunications networks, such as cellular communication networks,satellite networks, and the like.

Input/output devices 1318 may, in some implementations, include one ormore displays, distance determining elements, imaging devices, thermalsensors, infrared sensors, time of flight sensors, accelerometers,pressure sensors, weather sensors, cameras, gimbals, etc. Multipleinput/output devices 1318 may be present and controlled by the UAVcontrol system 1314.

As shown in FIG. 13, the memory may include program instructions 1322,which may be configured to implement the example routines and/orsub-routines described herein. The data storage 1324 may include variousdata stores for maintaining data items that may be provided fordetermining flight paths, landing, identifying locations for disengagingpayloads, engaging/disengaging the thrusting motors, etc. In variousimplementations, the parameter values and other data illustrated hereinas being included in one or more data stores may be combined with otherinformation not described or may be partitioned differently into more,fewer, or different data structures. In some implementations, datastores may be physically located in one memory or may be distributedamong two or more memories.

Those skilled in the art will appreciate that the UAV control system1314 is merely illustrative and is not intended to limit the scope ofthe present disclosure. In particular, the computing system and devicesmay include any combination of hardware or software that can perform theindicated functions. The UAV control system 1314 may also be connectedto other devices that are not illustrated, or instead may operate as astand-alone system. In addition, the functionality provided by theillustrated components may, in some implementations, be combined infewer components or distributed in additional components. Similarly, insome implementations, the functionality of some of the illustratedcomponents may not be provided and/or other additional functionality maybe available.

Those skilled in the art will also appreciate that, while various itemsare illustrated as being stored in memory or storage while being used,these items or portions of them may be transferred between memory andother storage devices for purposes of memory management and dataintegrity. Alternatively, in other implementations, some or all of thesoftware components may execute in memory on another device andcommunicate with the illustrated UAV control system 1314. Some or all ofthe system components or data structures may also be stored (e.g., asinstructions or structured data) on a non-transitory,computer-accessible medium or a portable article to be read by anappropriate drive. In some implementations, instructions stored on acomputer-accessible medium separate from the UAV control system 1314 maybe transmitted to the UAV control system 1314 via transmission media orsignals such as electrical, electromagnetic, or digital signals,conveyed via a communication medium such as a wireless link. Variousimplementations may further include receiving, sending, or storinginstructions and/or data implemented in accordance with the foregoingdescription upon a computer-accessible medium. Accordingly, thetechniques described herein may be practiced with other UAV controlsystem configurations.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described. Rather,the specific features and acts are disclosed as exemplary forms ofimplementing the claims.

What is claimed is:
 1. An unmanned aerial vehicle (“UAV”), comprising: abody; a plurality of motors coupled to the body; a support couplingconfigured to couple the body of the UAV and a landing gear assembly;the landing gear assembly, including: a plurality of landing gearextensions, each of the plurality of landing gear extensions contactinga surface and supporting at least a portion of the UAV, wherein at leasta first landing gear extension of the plurality of landing gearextensions is adjustable by a landing gear controller between a firstcontracted position and a first extended position independently ofothers of the plurality of landing gear extensions; and the landing gearcontroller configured to at least: monitor an angle of at least aportion of the body of the UAV with respect to a plane that isapproximately perpendicular to a gradient of a gravity field of earth ata position of the UAV; and adjust at least the first landing gearextension until the at least a portion of the body of the UAV isapproximately contained in the plane; wherein the support coupling isfurther configured to enable rotation of the body of the UAV about anaxis.
 2. The UAV of claim 1, wherein at least the first landing gearextension includes at least one of a hydraulic arm, a pneumatic arm, athreaded extension, a magnetically adjustable arm, a linear gearextension, or a telescoping arm.
 3. The UAV of claim 1, wherein theplurality of landing gear extensions further includes: a second landinggear extension of the plurality of landing gear extensions that isadjustable by the landing gear controller between a second contractedposition and a second extended position; and a third landing gearextension of the plurality of landing gear extensions that is adjustableby the landing gear controller between a third contracted position and athird extended position.
 4. The UAV of claim 1, further comprising: anavigation component configured to control a flight of the UAV; andwherein the navigation component is calibrated in response to acommunication from the landing gear controller that the at least aportion of the UAV is contained within the plane.
 5. A landing gearassembly for an unmanned aerial vehicle (UAV), comprising: a pluralityof landing gear extensions, each of the plurality of landing gearextensions coupled to and extending from the UAV, at least a firstlanding gear extension of the plurality of landing gear extensionsadjustable by a landing gear controller between a first contractedposition and a first extended position independently of others of theplurality of landing gear extensions; and a support coupling configuredto couple the plurality of landing gear extensions and a body of theUAV; and wherein the landing gear controller adjusts at least the firstlanding gear extension so that the body of the UAV is approximatelyhorizontal when landed on a surface, and wherein the support coupling isfurther configured to enable rotation of the body of the UAV about anaxis.
 6. The landing gear assembly of claim 5, further comprising; amain support base, the plurality of landing gear extensions beingcoupled to and extending from the main support base; and wherein thesupport coupling is configured to selectively couple and decouple themain support base and the body of the UAV.
 7. The landing gear assemblyof claim 5, wherein the plurality of landing gear extensions furtherincludes: a second landing gear extension of the plurality of landinggear extensions that is adjustable by the landing gear controllerbetween a second contracted position and a second extended position; anda third landing gear extension of the plurality of landing gearextensions that is adjustable by the landing gear controller between athird contracted position and a third extended position.
 8. The landinggear assembly of claim 5, wherein the support coupling includes a gimbalthat enables the rotation of the body of the UAV about an axis.
 9. Thelanding gear assembly of claim 5, further comprising: a contact sensorcoupled to the first landing gear extension configured to detect acontact between the first landing gear extension and the surface. 10.The landing gear assembly of claim 5, further comprising: a distancedetermining element configured to measure a distance between thedistance determining element and the surface.
 11. The landing gearassembly of claim 10, wherein: the measured distance is provided to thelanding gear controller; and the landing gear controller is configuredto determine an amount to adjust at least the first landing gearextension based at least in part on the measured distance and a desiredangle of the body of the UAV when the UAV is landed on the surface. 12.The landing gear assembly of claim 11, wherein the desired angle of thebody of the UAV is approximately horizontal.
 13. The landing gearassembly of claim 7, further comprising: a first distance determiningelement coupled to the first landing gear extension and configured tomeasure a first distance between the first landing gear extension andthe surface; a second distance determining element coupled to the secondlanding gear extension and configured to measure a second distancebetween the second landing gear extension and the surface; and a thirddistance determining element coupled to the third landing gear extensionand configured to measure a third distance between the third landinggear extension and the surface.
 14. A method to land an unmanned aerialvehicle (“UAV”), the method comprising: measuring, with at least onedistance determining element, a slope of a surface; and extending afirst landing gear extension of a plurality of landing gear extensions,independently of others of the plurality of landing gear extensions,from a first contracted position, in which the first landing gearextension has a first contracted length, to a first extended position,in which the first landing gear extension has a first extended length,wherein the first extended length is greater than the first contractedlength; wherein: the plurality of landing gear extensions comprises atleast a portion of a landing gear assembly, the landing gear assemblyconfigured to couple to a body of the UAV via a support coupling; thesupport coupling is further configured to enable rotation of the body ofthe UAV about an axis; and the first extended length is based at leastin part on the slope of the surface.
 15. The method of claim 14, furthercomprising: detecting a contact between a second landing gear extensionof the plurality of landing gear extensions and the surface; andwherein: the first landing gear extension is extended in response to thedetected contact; and the first extended position is determined inresponse to the first landing gear extension contacting the surface. 16.The method of claim 14, further comprising: detecting a contact betweena second landing gear extension of the plurality of landing gearextensions and the surface; and wherein: the first landing gearextension is extended in response to the detected contact; and the firstextended position is determined so that at least a portion of the UAV iscontained in a horizontal plane.
 17. The method of claim 14, furthercomprising: extending a third landing gear extension of the plurality oflanding gear extensions from a third contracted position, in which thethird landing gear extension has a third contracted length, to a thirdextended position, in which the third landing gear extension has a thirdextended length, until the third landing gear extension contacts thesurface.
 18. The method of claim 14, further comprising: determining adesired heading of the UAV; and rotating the body of the UAV, via thesupport coupling and without rotating the landing gear assembly, aboutthe axis to orient the body of the UAV in the desired heading.
 19. Themethod of claim 14, further comprising: determining that the UAV haslanded on the surface; contracting at least the first landing gearextension; determining that a payload of the UAV has contacted thesurface; and disengaging the payload from the UAV.